1. Field of the Invention
The present invention relates to an image forming apparatus such as a printer for printing the digital information by using an electro photography, a multifunctional printer mounting an image reading apparatus at its upper part on the printer body as a base, and a printer provided with a sheet processing device or the like.
2. Description of the Related Art
Depending on digitalization of the information and an IT revolution or the like, a printer as one example of an image forming apparatus has been widely used and developed from a business use to a personal use and from monochrome to color. On the other hand, development of digitalization contributes to a complex function of the printer. Therefore, a printer characterized as an output of an information terminal such as a personal computer or the like so far has been characterized also as a product to integrate the functions such as a copying machine, a facsimile machine, and an image input apparatus or the like that are independent functions conventionally.
It is because a technical base of developing a new product characterized by a high cost performance and a little space such as plural functions by one machine has been put into place. A typical example of the product is a MFC (multifunction copier) which is made by digitalizing and giving a network function to the conventional copying machine or a MFP (multifunction printer) which is made by giving an image input function to the conventional printer.
According to such an image forming apparatus, a printed sheet is reversed in the middle of a path to convey the sheet by a sheet reversing apparatus that is provided in the image forming apparatus so as to be so-called FD (face down) discharged from a sheet discharge port disposed on a side of the image forming main body of the apparatus to a loading tray. Alternatively, without reversed, the printed sheet passes through the path so as to be so-called FU (face up) discharged from the sheet discharge port to the loading tray (refer to JP-A-09-086757).
According to such a conventional image forming apparatus, in the case that a sheet post-processing device for performing the processing to the sheet is not mounted, the sheet to be discharged from the discharge port of the image forming main body of the apparatus is discharged on the loading tray that is disposed at the side of the body. If a predetermined amount of the sheet is loaded on the loading tray, when the load amount attains to a predetermined upper limit a full load detection sensor flag that is disposed on the side of the image forming apparatus is mounted on the uppermost sheet, the full load detection sensor flag turns off a full load detection sensor, and the image forming apparatus stops its operation by an OFF signal from the full load detection sensor.
On the other hand, a sheet post-processing device may be disposed at the side surface of the sheet discharge port side. As the sheet post-processing device, a staple stacker has been known, which is disposed at the side surface of the sheet discharge port side of the image forming main body of the apparatus, adjusts respective end portions of the sheets sequentially fed from the sheet discharge port of the image forming main body of the apparatus, carries out the post-processing such as staple (pin) or the like, and discharge the sheets.
However, according to such a conventional image forming apparatus, when carrying out the operation such as jam clearance operation or the like at the periphery of the sheet discharge port, it is necessary to detach the parts such as an exterior at the periphery of the sheet discharge port and the sheet post-processing device. In this case, the full load detection sensor flag is left at an initial position. Therefore, the full load detection sensor flag interferes with the operation such as the jam clearance operation or the like and this sometimes involves a problem that the full load detection sensor flag is damaged.
In addition, the configuration of a connection part becomes complicated upon installation of the image forming apparatus on the sheet post-processing device, so that there is a problem that the cost becomes high and reliability is lowered due to increase of the number of the parts.